H-II Transfer Vehicle

The H-II Transfer Vehicle, abbreviated HTV and also called Kounotori, the white stork, was an expendable Japanese automated cargo spacecraft designed to resupply the International Space Station, particularly the Japanese Kibo laboratory module. Development began in the early 1990s and the first mission, HTV-1, was launched on an H-IIB rocket on 10 September 2009. About 9.8 metres long and 4.4 metres across, it had an empty mass of 10,500 kilograms and a maximum launch weight of 16,500 kilograms, and it combined a pressurised carrier, an unpressurised carrier and a main body holding the avionics and propulsion. It was the only vehicle able to carry and dispose of the large International Standard Payload Racks of the station after the Space Shuttle retired. Nine missions flew, the last in May 2020, each ending with the vehicle loaded with waste and burned up over the Pacific; the improved HTV-X made its first flight in October 2025.